Water Pump

ABSTRACT

A flow guide plate is disposed downstream from an end portion of a tongue part in a volute chamber, and configured to reduce flow velocity of cooling water flowing at an outer peripheral side of the volute chamber, wherein the volute chamber includes a downstream side leading to a discharge opening, and wherein the tongue part separates the downstream side and an upstream side of the volute chamber from each other.

TECHNICAL FIELD

The present invention relates to a water pump.

BACKGROUND ART

A patent document 1 discloses an art of this kind. Patent document 1 discloses a pump including a separation wall, wherein the separation wall separates a curved flow path into a first flow path and a second flow path, and wherein the curved flow path communicates with a discharge pipe,

PRIOR ART DOCUMENT(S) Patent Document(s)

Patent Document 1: Japanese Patent Application Publication No, 2001-336499

SUMMARY OF THE INVENTION Problem(s) to be Solved by the Invention

According to the art described in patent document 1, the separation wall is disposed to extend beyond half of the curved flow path, This may adversely affect the efficiency due to a large loss in flow velocity. The present invention is made with attention to this problem, It is an object of the present invention to provide a water pump whose efficiency can be enhanced.

Means to Solve the Problem(s)

According to the present invention, in order to accomplish the object described above, a flow guide plate is disposed downstream from an end portion of a tongue part in a volute chamber, and configured to reduce flow velocity of cooling water flowing at an outer peripheral side of the volute chamber, wherein the volute chamber includes a downstream side leading to a discharge opening, and wherein the tongue part separates the downstream side and an upstream side of the volute chamber from each other.

Effect(s) of the Invention

Thereby, the present invention can enhance the pumping efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electric water pump according to a first embodiment.

FIG. 2 is a view of the electric water pump according to the first embodiment in a state where a pump cover is removed.

FIG. 3 is a view showing a flow of cooling water in a volute chamber in a case where no flow guide plate is provided.

FIG. 4 is a view showing a flow of cooling water in a volute chamber in the first embodiment where a flow guide plate is provided.

FIG. 5 is a view of an electric water pump according to a second embodiment in a state where a pump cover is removed.

MODE(S) FOR CARRYING OUT THE INVENTION First Embodiment

An electric water pump 1 according to a first embodiment is a cooling pump that employs a cooling medium (cooling water) as a working fluid, and is installed in a circulating circuit connected to a heat exchanger (radiator). For example, electric water pump 1 is a water pump for supplying cooling water to an engine (internal combustion engine), a driving motor, an inverter, etc., in a hybrid electric vehicle. FIG. 1 is a perspective view of electric water pump 1. Electric water pump 1 is accommodated in a pump housing 2. Pump housing 2 is composed of a pump body 21 and a pump cover 22. Pump cover 22 is formed with a suction opening 23 and a discharge opening 24. An impeller 3 having a plurality of blades 30 is disposed to rotate in electric water pump 1, wherein rotation of impeller 3 serves to suck cooling water through suction opening 23 and discharges the cooling water through discharge opening 24. FIG. 2 is a view of electric water pump 1 in a state where pump cover 22 is removed. Impeller 3 is accommodated in a space (impeller accommodation part 26) formed internally by pump body 21 and pump cover 22. Impeller 3 is mounted rotatably to a rotation shaft 25 fixed to pump body 21, At an outer periphery of impeller accommodation part 26, a volute chamber 27 is formed as a volute groove. Volute chamber 27 is formed in a volute shape having a beginning end at a point A in FIG. 2, and extending in the same direction as the direction of rotation of impeller 3 (clockwise direction in FIG. 2). In the following, a backward side of volute chamber 27 in the direction of rotation of impeller 3 is referred as upstream side, and a forward side of volute chamber 27 in the direction of rotation of impeller 3 is referred to as downstream side. Volute chamber 27 includes a discharge-opening-connecting portion 27 a at a downstream end, wherein discharge-opening-connecting portion 27 a is connected to discharge opening 24 of the pump cover, Discharge-opening-connecting portion 27 a includes a lateral surface having an arc shape. Pump body 21 is formed with a tongue part 21 a that separates the upstream side and the downstream side from each other, A flow guide plate 28 is formed in volute chamber 27. Flow guide plate 28 divides a part of volute chamber 27 into two flow paths. Flow guide plate 28 is formed to have the same height as volute chamber 27. Flow guide plate 28 is disposed in a downstream side of volute chamber 27, and includes an upstream end portion 28 a located downstream from an end portion of tongue part 21 a, Flow guide plate 28 includes a downstream end portion 28 b, which extends to discharge-opening-connecting portion 27 a but is out of contact with the lateral surface of discharge-opening-connecting portion 27 a, The upstream end portion 28 a of flow guide plate 28 is located closer to an outer periphery of volute chamber 27 with respect to a midpoint (on a line B) of volute chamber 27 in a transverse direction of volute chamber 27, whereas the downstream end portion 28 b of flow guide plate 28 is located closer to an inner periphery of volute chamber 27 with respect to the midpoint (on line B) of volute chamber 27 in the transverse direction of volute chamber 27.

Operation

FIG. 3 is a view showing a flow of cooling water in volute chamber 27 in a case where no flow guide plate 28 is provided. Cooling water is sucked through suction opening 23 by rotation of impeller 3, and is sent to volute chamber 27 by centrifugal force, and flows in the same direction as the rotational direction of impeller 3. Under this condition, the flow velocity at the outer peripheral side of volute chamber 27 is faster than the flow velocity at the inner peripheral side of volute chamber 27. Accordingly, at the discharge-opening-connecting portion 27 a of volute chamber 27, a swirl flow occurs which flows from the outer peripheral side to the inner peripheral side, so that cooling water flows along the wall surface of discharge opening 24 and a pipe connected to discharge opening 24. This causes a frictional loss with the wall surface, and the friction raises the temperature of cooling water and adversely affects the cooling efficiency. In this viewpoint, in the first embodiment, volute chamber 27 is provided with flow guide plate 28, to reduce the flow velocity of cooing water at the outer peripheral side of volute chamber 27. FIG. 4 is a view showing a flow of cooling water in volute chamber 27 in the first embodiment where flow guide plate 28 is provided. The flow guide plate 28 according to the first embodiment includes upstream end portion 28 a located closer to the outer periphery of volute chamber 27 with respect to the midpoint of volute chamber 27 in the transverse direction of volute chamber 27, and downstream end portion 28 b located closer to the inner periphery of volute chamber 27 with respect to the midpoint of volute chamber 27 in the transverse direction of volute chamber 27. Accordingly, the flow at the outer peripheral side of volute chamber 27 enters at a narrower inlet and exits at a wider outlet, so that the flow velocity decreases. On the other hand, the flow at the outer peripheral side of volute chamber 27 enters at a wider inlet and exits at a narrower outlet, so that the flow velocity increases. Thereby, at the discharge-opening-connecting portion 27 a of volute chamber 27, the flow of cooling water at the outer peripheral side and the flow of cooling water at the inner peripheral side cancel each other, to prevent the occurrence of a swirl flow. This serves to reduce the frictional loss occurring with the wall surface of discharge opening 24 and the pipe connected to discharge opening 24, and suppress the temperature of cooling water from rising, and thereby enhance the pumping efficiency. Moreover, flow guide plate 28 is located downstream from the end portion of tongue part 21 a of volute chamber 27. This serves to shorten the length of flow guide plate 28, and thereby reduce the flow channel resistance, and thereby enhance the pumping efficiency.

Effects

<1> It includes: a pump housing (2) formed with a suction opening (23) and a discharge opening (24); an impeller (3) arranged rotatably in an impeller accommodation part (26) of the pump housing (2), and configured to suck cooling water through the suction opening (23) and discharge the cooling water through the discharge opening (24); a volute chamber (27) formed in a volute shape at an outer periphery of the impeller accommodation part (26), and including a downstream side leading to the discharge opening (24); a tongue part (21 a) separating the downstream side and an upstream side of the volute chamber (27) from each other; and a flow guide plate (28) disposed downstream from an end portion of the tongue part (21 a) in the volute chamber (27), and configured to reduce flow velocity of cooling water flowing at an outer peripheral side of the volute chamber (27). Accordingly, at the discharge-opening-connecting portion 27 a of volute chamber 27, the flow of cooling water at the outer peripheral side and the flow of cooling water at the inner peripheral side cancel each other, to prevent the occurrence of a swirl flow.

<2> The flow guide plate (28) includes an upstream end (28 a) located closer to an outer periphery of the volute chamber (27) with respect to a midpoint of the volute chamber (27) in a transverse direction of the volute chamber (27); and the flow guide plate (28) includes a downstream end (28 b) located closer to an inner periphery of the volute chamber (27) with respect to the midpoint of the volute chamber (27) in the transverse direction of the volute chamber (27). Accordingly, flow guide plate 28 serves to reduce the flow velocity at the outer peripheral side of volute chamber 27, so that at the discharge-opening-connecting portion 27 a of volute chamber 27, the flow of cooling water at the outer peripheral side and the flow of cooling water at the inner peripheral side cancel each other, to prevent the occurrence of a swirl flow.

Second Embodiment

The following describes an electric water pump 1 according to a second embodiment. With regard to the same configuration as in the first embodiment, the same symbols are given and description thereof is omitted. FIG. 5 is a view of electric water pump 1 in a state where pump cover 22 is removed. A flow guide plate 28 is provided to extend from a lateral surface of discharge-opening-connecting portion 27 a into volute chamber 27. This serves to obstruct the flow from the outer peripheral side to the inner peripheral side at discharge-opening-connecting portion 27 a, and thereby prevent the occurrence of a swirl flow.

Effects

<3> The flow guide plate 28 is formed to extend from the lateral surface of discharge-opening-connecting portion 27 a of the volute chamber 27 into the volute chamber 27. This serves to obstruct the flow from the outer peripheral side to the inner peripheral side at discharge-opening-connecting portion 27 a, and thereby prevent the occurrence of a swirl flow.

Other Embodiments

Although the present invention has been described above by reference to the first embodiment and the second embodiment, specific configuration of the present invention is not limited to these embodiments, The present invention includes modifications in design if such modifications are within the subject matter of the invention.

Description of Symbols

1 . . . Electric Water Pump

3 . . . impeller

21 a . . . Tongue Part

23 . . . Suction Opening

24 . . . Discharge Opening

26 . . . Impeller Accommodation Part

27 . . . Volute Chamber

28 . . . Flow Guide Plate 

1. A water pump comprising: a pump housing formed with a suction opening and a discharge opening; an impeller arranged rotatably in an impeller accommodation part of the pump housing, and configured to suck cooling water through the suction opening and discharge the cooling water through the discharge opening; a volute chamber formed in a volute shape at an outer periphery of the impeller accommodation part, and including a downstream side leading to the discharge opening; a tongue part separating the downstream side and an upstream side of the volute chamber from each other; and a flow guide plate disposed downstream from an end portion of the tongue part in the volute chamber, and configured to reduce flow velocity of cooling water flowing at an outer peripheral side of the volute chamber.
 2. The water pump as claimed in claim 1, wherein: the flow guide plate includes an upstream end located closer to an outer periphery of the volute chamber with respect to a midpoint of the volute chamber in a transverse direction of the volute chamber; and the flow guide plate includes a downstream end located closer to an inner periphery of the volute chamber with respect to the midpoint of the volute chamber in the transverse direction of the volute chamber.
 3. The water pump as claimed in claim 1, wherein the flow guide plate is formed to extend from a lateral surface of a downstream end portion of the volute chamber into the volute chamber. 